70-51600-26-05671_Glenwood-Pond_FinalReport.pdf.PDF

New Mexico Department of Game and Fish

2024 DREDGING EVALUATION REPORT

GLENWOOD POND, GLENWOOD, NEW MEXICO

FINAL

February 2025

Dredging Evaluation for Glenwood Pond

FINAL

February 12, 2025

PRESENTED TO PRESENTED BY

New Mexico Department of Game & Fish 1 Wildlife Way Santa Fe, New Mexico 87507

Tetra Tech, Inc.

6121 Indian School Rd NE Suite 205 Albuquerque, NM 87110 tetratech.com

Prepared by:

Name Jelena Gribic Title Environmental Scientist

Date 2/20/25

Reviewed by:

Name: Ondrea Hummel Date Title: Senior Ecologist 2/20/25

Reviewed by:

Name: Walt Kuhn Title: Senior Hydraulic Engineer

2/20/25 i

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 BATHYMETRIC SURVEY

3.0 SURVEY POST-PROCESSING

4.0 SEDIMENT SAMPLING

4.1 Sediment Collection Methods

4.2 Lab Analysis

4.3 Sediment Results

4.3.1 Results Assessment Method

4.4 Additional Findings

5.0 SUMMARY AND RECOMMENDATIONS

5.1 Dredging

5.1.1 Bathymetric Results

5.1.2 Sediment Quality Results

5.2 Aquatic Vegetation

6.0 BIBLIOGRAPHY

LIST OF TABLES

Table 1: Survey control for the November 2024 Survey Table 2. Sediment Sample Processing - Lab Analysis Method Analytes Table 3. Glenwood Pond metal contaminant results by sampling locations in mg/KG, average by metal, and percent difference between site values by metal Table 4. Glenwood Pond sediment metal concentrations compared to selected criteria Table 5. Glenwood Pond nutrient concentration results by sampling locations in mg/KG, average by element, percent change element, and N:P ratio Table 6. Glenwood Pond sediment nutrient concentrations compared to selected criteria

LIST OF FIGURES

Figure 1. Bathymetric and LiDAR survey data, and location of sediment samples (S1 – inlet; S2 – outlet) Figure 2. Photo of Glenwood Pond taken from a southeast direction on November 2024 survey Figure 3. Digital Terrain Model based on November 2024 survey Figure 4. 0.5-foot interval Contour Mapping of Glenwood Pond Figure 5. Aerial of Glenwood Pond showing potential management zones Figure 6. Potential Dredge Area

APPENDICES

Appendix A: Field Notes Appendix B: Sediment Sample Lab Test Results

1.0 INTRODUCTION

The New Mexico Department of Game and Fish (NMDGF) is evaluating dredging Glenwood Pond to improve fish habitat. Glenwood Pond is approximately 400 feet long by 150 feet wide and is popular for recreational fishing (Figure 1). It is located immediately downstream of the Glenwood State Fish Hatchery, and adjacent to Whitewater Creek. It is within the town of Glenwood, Catron County, New Mexico, about 10 miles east of Arizona. It is in the Whitewater Creek Watershed (HUC-10), and greater San Francisco Watershed.

Glenwood Pond is fed by outflow from the Glenwood State Fish Hatchery which currently raises native Gila trout (Oncorhynchus gilae), a federal and state-listed threatened species found in a small number of mountain water streams in Arizona and New Mexico. Management direction for Glenwood Pond is to be a “put and take” fishery, with the stocking goals of: “(1) stock catchable triploid rainbow trout annually, and (2) initiate stocking Gila trout in Glenwood Pond (p. 155, NMDGF, 2022). with the intent of transitioning to only stocking Gila trout in Glenwood Pond.” Anglers frequent the pond to fish for trout species and enjoy the riparian setting. Other fish found in the adjacent Whitewater Creek include federal and state-listed endangered species loach minnow (Rhinichthys cobitis).

The portion of Whitewater Creek that runs directly adjacent to the pond is currently assessed as meeting water quality attainment standards by the EPA, however, the upstream portions of Whitewater Creek are impaired/303(d) listed and a restoration plan has been put in place through a TMDL plan (EPA, 2024).

To evaluate dredging options, Tetra Tech performed a bathymetric survey of the pond on November 4, 2024. Sediment samples were also collected for laboratory analysis. The survey data was post-processed, and a Digital Terrain Model (DTM) was developed to represent the pond bed elevations and depths. Two sediment samples were collected for analysis of heavy metals, phosphorus, and nitrogen.

The NMDGF project managers and team for this study were Jack Marchetti and Michael Ruhl. Walt Kuhn, PE, served as the project manager for Tetra Tech, Inc. A bathymetric survey and sediment sampling was performed on November 4, 2024, by Dai Thomas, PhD, PE, and Jelena Grbic, M.Sc., Ms. Grbic post-processed the survey data and Dylan Monahan interpreted the sediment sample results. Quality control review was provided by Walt Kuhn, Dai Thomas, and Ondrea Hummel.

This report presents the bathymetric survey and sediment sampling collection methods, including post-processing results and recommendations, which will provide baseline data needed to inform dredging plans.

Figure 1. Bathymetric and LiDAR survey data, and location of sediment samples (S1 – inlet; S2 – outlet)

2.0 BATHYMETRIC SURVEY

To perform the survey, a Leica GS16 Global Navigation Satellite System (GNSS) receiver was set over a benchmark (also referred to as a survey control). The receiver was used as a base station and provided real-time kinematic (RTK) correction to a Leica Viva GS16 rover via a radio. The rover was linked to a Sonarmite single beam echosounder (± 0.1-foot resolution), which were mounted in an inflatable kayak, specifically constructed for performing surveys. Position and depth data were collected in a Leica Controller (Model No. CS20.3.75G).

NMDGF provided coordinates for a benchmark located near the end of a concrete wall, which the base station was set over. However, based on mapping and the subsequent survey, the benchmark coordinates appeared to be about 150 feet off from the actual location, and therefore, the NMDGF coordinates were not used.

The base station collected static position data for an approximately 5-hour period. The static survey data were sent to the National Geodetic Survey (NGS) Online Positioning User Service (OPUS) (http://www.ngs.noaa.gov/OPUS) to provide an accurate location of the survey benchmark. The rover survey data were adjusted to the base station location in an Excel spreadsheet (Table 1). The horizontal datum for the survey was referenced to the North American Datum of 1983 (NAD83) State Plane New Mexico West FIPS 3003 (US Feet) projection and the vertical datum referenced to the North American Vertical Datum of 1988 (NAVD88).

Table 1: Survey control for the November 2024 Survey

State Plane New Mexico West FIPS 3003 (US Feet)

Easting Northing Elevation

(NAVD88)

2,403,417.51 846,112.43 4,734.53

Due to the shallow depth and significant vegetation cover over the majority of the lake, the survey was performed using an inflatable kayak as opposed to using a small boat with an outboard engine. The surface vegetation and low-lying and partially submerged tree branches near the western edge of the pond restricted boating.

The following submerged aquatic vegetation (SAV) was noted to be present in excess: duckweed species (genus Lemna) at the surface of the pond, and a milfoil species (genus Myriophyllum) rooted into the bottom of the pond (Figure 2). Survey data was collected along transects at an approximately 25-foot spacing and the rover was configured to automatically collect bathymetric points every 10 feet along the transect.

During the survey, there was a poor radio signal to the rover from about the center to the far end of the lake, which resulted in poor position accuracy. The survey points were assessed based on the field knowledge and were deemed reasonable, and therefore were used for post-processing. Any error in the position would likely have a small impact of the resulting DTM.

The pond water-surface elevation at the time of the survey was 4,734.01 feet, based on an average of three measurements collected with the rover.

Figure 2. Photo of Glenwood Pond taken from a southeast direction on November 2024 survey

3.0 SURVEY POST-PROCESSING

Following the survey, the data was post-processed in ArcPro, a Geographical Information System (GIS) software package. The data were used to develop a Triangular Irregular Network (TIN) surface, which was then converted into a DTM.

The post-processing included removing points that were deemed erroneously high or low based on trends with neighboring points; these erroneous points were likely caused by the vegetation or depths less than

0.5 feet. Additional points were deleted that were not beneficial in the development of the TIN (e.g. points that were collected perpendicular to the transect and collected navigating between transects).

To improve the TIN, additional above water ground points were added around the margin of the pond.

The ground points were obtained from a Light Detection and Ranging (LiDAR) survey. The LiDAR data was obtained from the University of New Mexico (RGIS, 2024) and was acquired on April 3, 2019.

The LiDAR data was used to develop the dry land section of the DTM, which in turn was used to create contours at 0.03-meter intervals (~0.1 feet). Points were subsequently generated at the contour of the surveyed water surface elevation and used to define the perimeter of the pond (Figure 1).

The DTM was created in ArcPro from the combination of bathymetry data (4,732 feet to 4,729 feet), and the 2019 LiDAR data (elevation at 4733 feet). The combined elevations were used to create a TIN using the Delaunay triangulation method. TINs create a vector based continuous surface where each point is connected to form a network of triangles. The TIN was used to create a DTM in raster format with a 10-foot cell size (Figure 3). Elevation contours were created using 0.5-foot intervals (Figure 4). Based on the DTM, the bed elevations ranged from 4728.6 to 4733.3 with an average depth of 4.1 feet.

To our knowledge, no historical bathymetric data is available for comparison with the 2024 survey data to assess changes in the pond bathymetry.

Figure 3. Digital Terrain Model based on November 2024 survey

Figure 4. 0.5-foot interval Contour Mapping of Glenwood Pond

4.0 SEDIMENT SAMPLING

Sediment samples were collected at two locations. S1 was collected near the northeast end of the pond near the culvert inlet receiving water from the fish hatchery, and S2 was collected near the southeast end of the pond (Figure 1). Field notes are provided in Appendix A.

4.1 SEDIMENT COLLECTION METHODS

The sediment samples were collected using a hand corer (small hand push corer - 2.5” diameter x 3 feet core tube) with a 20-foot push rod. The sediment was collected with the corer and an attached “T” handle, allowing the sampler to be pushed into the sediment. Sediment was trapped in a clear PVC tube with a rubber stopper then transferred to shore and placed on a clean tarp. A subsample was obtained from the sediment sample by taking material from the bottom, middle, and top sections of the core and placing it in a glass sample jar. Samples were then placed on ice to maintain a temperature of < 6˚ Celsius (Eurofins, 2016) and a chain of custody maintained for sample handling. The tarp was rinsed with pond water between samples and a new PVC pipe used for the subsequent sample. Sediment analysis was tested by Eurofins Albuquerque, NM (Formerly Hall Environmental).

4.2 LAB ANALYSIS

Eurofins Albuquerque tested the sediment samples for metals, anions, and general chemistry (phosphorus, nitrogen, ammonia). Samples were processed between November 11, 2024, and December 03, 2024.

Analytes and lab test methods are listed in Table 2. Sediment Sample Processing - Lab Analysis Method

Analytes. The detailed lab data report is provided in Appendix B. Concentrations of metals and nutrients were measured from core samples for each of the two lake sampling locations and were reported as mg/Kg dry weight.

Table 2. Sediment Sample Processing - Lab Analysis Method Analytes

Lab Analysis Method

Analyte CAS Number Unit

6010B 7429-90-5 Aluminum mg/kg

SM 4500 NH3 C 7664-41-7 Ammonia mg/kg

6020A 7440-38-2 Arsenic mg/kg

6020A 7440-43-9 Cadmium mg/kg

6020A 7440-47-3 Chromium mg/kg

6020A 7440-50-8 Copper mg/kg

6020A 7439-92-1 Lead mg/kg

6010B 7439-96-5 Manganese mg/kg

6010B 7440-02-0 Nickel mg/kg

300.0 14797-55-8 Nitrate mg/kg

300.0 14797-65-0 Nitrite mg/kg

Total Nitrogen STL00155 Nitrogen, Total mg/kg

SM 4500 NH3 C STL00296

Nitrogen, Total

Kjeldahl mg/kg

6020A 7440-22-4 Silver mg/kg

365.1 7723-14-0 Total Phosphorus as

P mg/kg

6010B 7440-66-6 Zinc mg/kg

4.3 SEDIMENT RESULTS

Metals and nutrients in a lake's surface water and sediment play an important role in shaping a lake's aquatic biological communities, influencing the health and composition of those communities. Metals at certain concentrations can be toxic to aquatic life, and excess nutrients in lake sediments can drive eutrophication. Lake sediment is a potential source of water column pollutants, and understanding the concentrations of both metals and nutrients is an important component of lake management, allowing managers to understand a possible source of metal and nutrient pollutants in the water column (Wang et

al. 2024). Lake sediments are also home to vital benthic biological communities, and sediments with toxic concentrations of metals or high nutrient loads will affect those benthic communities, which will have effects through the trophic levels.

4.3.1 Results Assessment Method

Lake sediment metals and nutrient concentrations were assessed separately because they have different potential adverse effects on lake ecosystems; excess metals are more likely to be toxic to aquatic life, and excess nutrients are more likely to cause eutrophication including algae blooms, and oxygen depletion events. Both nutrients and metals are assessed based on two criteria.

Between Site Comparison: Lake sediment composition is developed through a complex interaction of terrestrial and upstream inputs and the flow dynamics of the lake in question (Wang et al. 2024). Lake sediments are often reservoirs that house clues to historic watershed dynamics, watershed management, and potential water column pollutant sources. If there are spatial variations in lake sediment metals and nutrient concentrations, this information can provide important clues that inform future lake management actions, the source of anthropogenic inputs, and what the background conditions were; for this reason, between-site differences were assessed for each sampling location in Glenwood Pond.

o Sampling locations: Glenwood Pond Inlet and Glenwood Pond Outlet

Identification of Elevated Concentrations: Results were assessed to see if any of the recorded concentrations were high enough to raise management concerns. New Mexico does not have lake sediment criteria for either metals or nutrients. This assessment used the best available and relevant aquatic life criteria for metal and nutrient concentrations.

4.3.1.1 Metals

4.3.1.1.1 Between Site Comparison

On November 11th, 2024, Tetra Tech collected samples at the two Glenwood Pond sampling locations that were analyzed for metal concentrations: aluminum (Al), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), silver (Ag), and zinc (Zn).

Concentrations were evaluated for noticeable differences between sites at levels that may be relevant to future management considerations. Concentrations of sediment metals can vary significantly even in smaller lakes due to hydrologic dynamics, core depth, and the location of anthropogenic and/or natural sources (Wang et al. 2024). Because the Glenwood Pond sample size is 2; a non-statistical, best professional judgment (BPJ) comparison of metal concentrations between sites was used. Site metal concentration value, metal concentration average, and percentage difference of the metal values between sites were compared to identify differences that may affect future pond management. At other lake sites with three sample locations, we also assessed the average, geometric mean, and standard deviation. But with only two sampling locations at Glenwood, the percent difference from the average was thought to be a better comparison indicator.

The following metals were recorded as non-detects: As, Cd, Cr, Cu, and Ag. It is assumed in this analysis that if the metal concentration is a recorded non-detect at both sampling locations, there is no difference between the sampling location concentrations. Pb at Glenwood Inlet was also a non-detect, but we had a value for Pb at Glenwood Outlet. To determine if there is a difference in Pb concentrations between those two sites, the non-detect value was determined to be recorded as half of the sample's minimum detection value (MDV) (Smith 1991).

For the remaining metals shown in Table 3, four metal concentrations (Al, Pb, Mn, and Ni) have a percent difference from the average of over 100%. Differences >100% are highlighted in red. Percent differences over 100% do indicate potential differences between sites that the manager may want to explore further.

If lake management concerns require a more thorough understanding of possible differences, a more statistically robust study should be implemented with a larger sample size to establish a temporal and spatial gradient. There does not appear to be a difference in Zn values between sites.

Table 3. Glenwood Pond metal contaminant results by sampling locations in mg/KG, average by metal, and percent difference between site values by metal.

Units Metal Glenwood

Inlet Glenwood

Outlet Average

Percent Difference (from avg) mg/Kg

Aluminum (Al)

3500 11000 7250 104

11/11/24

Lead (Pb) 2.5* 13 7.8 133

Manganese (Mn)

21 90 55.5

Nickel (Ni) 2.5 8.5 5.5 109

Zinc (Zn) 23 32 27.5 33

Bold Values represent highest concentration recorded, values with percent differences over 100 are in red. *= non-detect value recorded as half of the MDV.

All the highest metal concentrations were found at the Glenwood Pond Outlet site and the lowest concentrations were found at the Glennwood Pond Inlet site. This could also account for the percent difference in Al, Pb, Mn, and Ni since there is more mixing and movement of water at the inlet site than the outlet site. Other factors could contribute to this difference (and that is where a larger sample size may aid in deciphering these differences if that level of detail is desired).

Finding higher metal concentrations at Glenwood Pond Outlet as opposed to the Glenwood Pond Inlet is surprising as, generally, higher concentrations are expected at the inflow of a lake or reservoir (Ciesl and Gruca-Rokosz 2024; Martinez et al. 2023). Factors dictating sediment transport and accumulation in reservoirs are complex and influenced by terrestrial inputs, upstream inputs, rates of metals released into surface water, and management (Melesse et al., 2011; Liu et al., 2019). The fact that higher concentrations are found at the outlet of Glenwood Pond Outlet could indicate that background inputs are greater than anthropogenic load inputs. However, it was observed in the field that the inlet region had greater flow (higher velocity), while downstream at the outlet sample, there was less water movement, indicating that material may settle here, especially in a somewhat smaller pond system. If management requires a more in-depth understanding of spatial concentrations of Glenwood Pond metals, the potential reasons for that, and to get a better understanding of the long-term trends then the collection of more samples is recommended.

4.3.1.1.2 Identifying Elevated Concentrations

An important management question is whether any potential lake sediment metal concentrations found during Glenwood Pond sampling are toxic to aquatic organisms. Because New Mexico does not have lake sediment mass aquatic life criteria, the best available aquatic life criteria were used for each metal.

• U.S. EPA, Region 5 Ecological Screening Levels (MacDonald et al 2000) (Pb, Ni)

• Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario (Persaud et al ., 1993) (Pb, Ni, Mn)

• Calculation and Evaluation of Sediment Effect Concentrations for the Amphipod Hyalella azteca and the Midge Chironomus riparian (Ingersoll et al 1996) (Al)

None of the contaminants exceeded the selected toxicity criteria (Table 4). It should be noted that using non-site-specific criteria can introduce biases, as aquatic life toxicity can depend on several site-specific relationships. The solubility of sediment metals of concern in surface water should also be considered when assessing long-term management goals. Solubility for specific metals, such as Al, depends on pH levels. The fact that all metal concentrations are below selected criteria suggests that sediment metal concentrations at Glenwood Pond are not a threat to aquatic life in the pond, or of concern when handling the sediment. If relevant to future management questions, the relationship between sediment metal concentrations as a source of surface water contamination should be explored in greater detail.

Table 4. Glenwood Pond sediment metal concentrations compared to selected criteria.

Units Metals Glenwood

Inlet Glenwood

Outlet

Ontario Lowest Effect Level

EPA

Region 5

Ingersel et al mg/Kg

Aluminum 3500 11000 NA NA 58000

Lead 2.5* 13 31 35.8 NA

Manganese 21 90 460 NA NA

Nickel 2.5 8.5 16 22.7 NA

Zinc 23 32 120 121 NA

*= non-detect value recorded as half of the MDV.

4.3.1.2 Nutrients

4.3.1.2.1 Between Site Comparison

On November 11th, 2024, Tetra Tech sampled the following nutrient concentrations at the two Glenwood Pond sampling locations: Glenwood Pond Inlet and Glenwood Pond Outlet: ammonia (NH3), nitrate (NO 3), nitrite (NO-2), total nitrogen (TN), total Kjeldahl nitrogen (TKN), and total phosphorus (TP).

Concentrations were evaluated for noticeable differences that may have management impacts between sites. Due to the sample size (2), a non-statistical, BPJ comparison of nutrient concentrations between sites was used.

Site nutrient concentration values, nutrient concentration averages, and percentage difference from the average of the nutrient values were calculated and used to understand the differences between location values. The following nutrients were recorded as non-detects at both sampling locations: NO3 and NO-2.

It is assumed in this analysis that if the nutrient concentration is a recorded non-detect at both sampling locations, there is no difference between the sampling location concentrations.

For the following nutrients, NH3 and TP (Table 5), using BPJ, none of the values were judged to represent a large enough difference between values or along a gradient of values to show that one site has a higher concentration of sediment nutrients, such to raise management concerns. TN and TKN have a percentage difference between sites of over 100% and, therefore, indicate a difference in concentrations.

Heterogeneity of lake concentrations of nutrient sediment levels between sites is not assumed; however, if management concerns require the determination of actual differences between sites for TN and TKN, we recommend collecting more samples at Glenwood Pond with a study design that increases spatial and temporal coverage.

Table 5. Glenwood Pond nutrient concentration results by sampling locations in mg/KG, average by element, percent change element.

Units Nutrient Glenwood

Inlet Glenwood

Outlet Average

Percent Difference (from avg)

Date

Mg/Kg

Ammonia 110 63 86.5 54.3

11/11/24

Nitrogen, Total

1500 490 995 101.5

Nitrogen, Total

Kjeldahl 1500 490 995 101.5

Total Phosphorus

29 17 23 52.2

Bold Values represent highest concentration recorded, values with percent differences over 100 are in red.

Sampling location Glenwood Pond Inlet has the highest recorded sediment nutrient concentration values.

Finding higher sediment nutrient concentrations at the inlet is an expected result, as nutrient concentrations are often higher at the inlet due to upstream inputs.

The low percent difference (Table 5) between NH3 (54.3%) and TP (52.2%) suggests that more sampling might help determine if the differences between Inlet and Outlet for those two nutrients is a consistent trend. The fact that at both sites TN is at a higher concentration than TP (Table 5), indicates that TP is a limiting nutrient in Glenwood Pond; this has management implications because additional TP inputs could result in algae blooms. Further sampling is recommended if management wants a more thorough picture of the N:P dynamics in the pond, especially related to vegetative growth (see Section 4.4).

4.3.1.2.2 Identifying Elevated Concentrations

An important management question is whether any potential nutrient concentration found in lake sediments is harmful to aquatic organisms. Because New Mexico does not have lake sediment aquatic life criteria, the best available aquatic life criteria were used for each nutrient (there is no relevant value for TN, but there is for TKN):

Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario (Persaud et al, 1993) (NH 3, TKN, TP)

Nutrient concentrations for NH3 and TKN at the inlet are above the Ontario Lowest Effects criteria as demonstrated in Table 6; Glenwood Inlet NH3 value is 110 mg/Kg and the Ontario Lowest Effects criteria for NH3 is 100 mg/KG, Glenwood Inlet TKN value in 1500 mg/Kg and the Ontario Lowest Effects criteria for TKN is 550 mg/Kg. All other nutrient values are below the selected criteria (Table 6).

High levels of NH3 can harm fish, and high TKM can lead to algae blooms. Management should include monitoring nutrients in surface water, pH, water temperature, and TP level and managing nutrient inputs to prevent long-term ramifications.

Table 6. Glenwood Pond sediment nutrient concentrations compared to selected criteria.

Units Nutrient Glenwood Inlet Glenwood

Outlet Ontario Lowest

Effect Level

Mg/Kg

Ammonia 110 63 100

Nitrogen, Total Kjeldahl

1500 490 550

Total Phosphorus 29 17 600

4.4 ADDITIONAL FINDINGS

Of note, there is a fair amount of submerged aquatic vegetation (SAV) in Glenwood Pond, both on the surface (duckweed; Lemnodia sp..) and most likely a native species of milfoil (Myriophyllum sp.). The milfoil species, assessed to the best of our knowledge based on field and photography evaluation, may be one of the three following species: Northern Watermilfoil (M. sibericum) or Whorled milfoil (M.

verticillatum) (which are both native); or non-native Eurasian Watermilfoil (M. spicatum). Preliminary identification of the specimen by field staff, including a botanist, was leaning towards an identification of one of the native milfoil species but the identification is not certain because of the lack of flowering stems and rhizomes to make a final determination. The vegetation can be seen both in the photo in Figure 2 and may be visible in Figure 5 below.

As part of the analysis and recommendations, it was also noted that most public use (in the form of fishing) was conducted near the parking lot and around the eastern side (as far as the southeastern portion where there is a concrete block to stand on) of the lake as shown in the outlined area in red in Figure 5.

It is assumed that the area not circled in red is left to provide more shaded habitat for fish species and that no dredging would be wanted along the pond edge in this area.

Based upon the desire for continued recreational use and proposed dredging to allow that continued use, additional recommendations are provided in Section 5 in relation to vegetation management.

Figure 5. Aerial of Glenwood Pond showing potential management zones

5.0 SUMMARY AND RECOMMENDATIONS

Below are recommendations for dredging based upon the study findings. These recommendations are based upon the following assumptions:

a) Dredging is desired to provide the best possible trout habitat within the lake and to remove fill that has entered the pond over the course of several decades. Dredging depths would be recommended based upon this assumption.

b) Sediment quality was evaluated for potential fish habitat in terms of:

a. Initiate stocking Gila trout with the intent of transitioning to only stocking Gila trout in

Glenwood Pond.

b. Any potential effects to fish while dredging is occurring (and if relocation of fish is needed based upon the results).

c. Any need for containment of or special processing of sediment removed from the lake.

c) Management of vegetation is desired to provide the best cold-water fisheries habitat within the main portions of the lake as well as provide refuge and shaded habitat along the northern and western sides of the lake which is currently protected by overhanging trees and a small area of sedge and rush species.

5.1 DREDGING

5.1.1 Bathymetric Results

Based upon the results and the assumptions noted above, we recommend limiting dredging along the northern and western sides of Glenwood Pond so as not to disturb the existing wetland and shore habitat.

It is recommended that dredging be concentrated in the center and along the east and south shores.

Specific implementation recommendations for the dredging are as follows:

a) Dredge as deep as possible based upon the project budget to create a cold-water fishery and to add overall capacity to the pond.

b) If possible, dredge to a gravel substrate to improve invertebrate diversity, depending on the depth of existing gravel.

To develop a volume of material to be dredged several assumptions were made. Currently the deepest part of Glenwood pond is approximately six feet deep near the southwest corner, while the rest of the middle of the pond varies between four and five feet deep. A new DTM was developed with a depth of nine feet over an area covering two thirds of the pond (Figure 6). Comparing the volume of the proposed conditions DTM to the volume of the existing conditions DTM a volume change of approximately 7000 cubic yards of material was calculated. This is the volume of the material that would need to be dredged from the pond. This volume estimate could be used to secure cost estimates from dredging contractors, however a detailed dredging plan should be developed that would have more diversity of depth in the center with deeper and shallower areas resulting in an average depth of nine feet, while leaving the existing areas near the banks as shallow water habitat. For example, additional area along the east bank may warrant being left undredged (to provide more buffer to this area).

Figure 6. Potential Dredge Area

5.1.2 Sediment Quality Results

Based upon the sediment testing results, the following is recommended:

a) As noted, with a sample size of two, it was not possible to perform statistical tests to gain a better understanding of spatial variability of sediment analyte concentrations. There were differences in metals, and nitrogen noted between the outlet and inlet samples.

o No metals were found to exceed aquatic life toxicity criteria, suggesting that metal sediment concentrations do not pose a threat to aquatic life in the pond. Based upon the test results for metals, these do not appear to be an issue for dredging or disposing of the material. If metals are of great concern to management, it is recommended to explore the relationship between sediment metal concentrations as a source of surface water contamination.

o Higher nutrient concentration values were noted at the inlet which was expected from upstream inputs. We recommend monitoring surface water NH3, TKN, TP, pH, and water temperature before, during, and after dredging. See below.

b) Dredge using best management practices to protect aquatic organisms from the adverse effects of the disturbance.

o Since TP was shown to be a limiting nutrient, it is noted that removal of sediment may improve this over time but that the mixing of sediment into the water column may cause a short-term temporary impact to water quality that the fish are using, especially turbidity.

It is recommended that this be monitored and/or fish be encouraged to move into a different quadrant of the lake than that being dredged.

Because of the high TKN level, monitoring TKN in the water column will inform management if TKN from the sediment is contributing to the water column. A high nitrogen level means additional TP inputs could result in algae blooms. In addition, watershed inputs of TKN and TN should be monitored and managed.

It is also recommended that if fish are moved to a different quadrant of the lake, that re-opening of the dredged area not be conducted until the sediment has returned to normal levels (prior to dredging).

c) It is also noted that removal of a portion of the SAV currently rooted in the sediment may be of benefit for overall fish habitat and potentially in relation to the nutrient findings.

d) Additional TP inputs could result in algae blooms. This may already be contributing to the high amount of SAV noted in the pond. Further sampling is recommended if management would like a more thorough picture of the N:P dynamics and management of SAV and potential algal populations.

e) A deeper depth will allow for development of topographic diversity or addition of benthic structure for refugia and habitat for benthic organisms, which also provide an important level of diversity in the food chain sources for fish species.

5.2 AQUATIC VEGETATION

Whether the Myriophyllum is native or non-native, management is recommended from a fish habitat perspective in terms of open water habitat.

a) If it is a native species, it is recommended that the bathymetric data be used to assess what shallow areas might benefit from native aquatic plant species structure for trout to use as prey cover and thermal modification this vegetative growth be kept to the pond edges and not further than 5 feet from the pond bank. Native and non-native plant management should also include monitoring and limiting phosphorus. As data suggest that might be a limiting factor at Glenwood Pond. Even with potentially limiting phosphorus, there is already a great deal of aquatic plant growth.

b) If this is non-native Myriophyllum spicatum, then treatment procedures for milfoil per state guidelines are recommended to be followed to keep this species at as reduced of a level as possible.

New Mexico lists M. spicatum as a Class C noxious weed and Priority Class 3 Aquatic Invasive Species (AIS), indicating that it is widespread in the state with ecological and economic impacts and management is difficult (NMDA, 2020; NM AIS Advisory Council, 2008). Any herbicide treatment should be approved for aquatic habitat and known potential effects to fish species so as to not affect fish species). There exist other management options that could be explored such as suction collection, and mechanical controls. Mechanical controls of the plant can further spread stem fragments and thus, cause further spread of the species. Removal by hand (potentially hand raking) could be an option if plant fragments are disposed of properly (Pfingsten et al., 2025).

Furthermore, signs should be placed at the pond to indicate the infestation and prevent further spread by fishing gear and lines.

Other management strategies should focus on fish habitat from an open water perspective.

a) It is recommended to assess potential shallow areas using bathymetric data to determine suitable locations for introducing native aquatic plant species. This could provide necessary structure for trout to use as prey cover and assist in thermal modification.

b) Monitoring and managing nutrient levels, particularly phosphorus, is crucial as it may act as a limiting factor in Glenwood Pond. Addressing nutrient inputs will help prevent potential algal blooms and improve overall water quality.

c) Additionally, signage should be placed around the pond to inform visitors about preserving the aquatic ecosystem and preventing any unintentional spread of aquatic invasive species (AIS) by cleaning fishing gear and lines. Decontamination of equipment should be conducted between waterways per the NMDGF AIS program (Aquatic Invasive Species - NMDGF).

6.0 BIBLIOGRAPHY

Breeding, Noreen A. 1996. Management plan for the Rio Cebolla watershed Sandoval County and Rio Arriba County, New Mexico. USFS.

Cieśla M, Gruca-Rokosz R. Fate of heavy metals in ecosystems of dam reservoirs: Transport, distribution and significance of the origin of organic matter. Environ Pollut. 2024 Nov 15;361:124811. doi:

10.1016/j.envpol.2024.124811. Epub 2024 Aug 25. PMID: 39191318.

Environmental Protection Agency (EPA). (2024). How's My Waterway. Retrieved from https://mywaterway.epa.gov/

Ingersoll CG, Haverland PS, Brunson EL, Canfield TJ, Dwyer FJ, Henke CE, Kemble NE, Mount DR, Fox RG (1996) Calculation and evaluation of sediment effect concentrations for the amphipod Hyalella azteca and the midge Chironomus riparius. J Great Lakes Res 22:602– 623

Liu N., Chen W., Lin J., Zhan Y. Contrasting effect of zirconium-, iron-, and zirconium/iron-modified attapulgites capping and amendment on phosphorus mobilization in sediment. Environ. Sci. Pollut. Res. 2022;29:18508– 18526. doi: 10.1007/s11356-021-16979-5.

MacDonald, D.D., Ingersol, C.G., and Berger, T.A. 2000. Development and Evaluation of Consensus-Based Sediment Quality Guidelines Freshwater Ecosystems. Archives of Environmental Contamination and Toxicology.

Martinez, Angela Ethelis Jimenez., Carlos Eduardo, Galoski., Rubens César Lopes, Figueira., Paulo Alves de Lima, Ferreira., and Sandro Froehner. 2023. 136 Years of variation of sediment-associated metals in a subtropical reservoir in southern Brazil: Implications for the environmental change, CATENA, Volume 231, 107315, ISSN 0341-8162, https://doi.org/10.1016/j.catena.2023.107315.

(https://www.sciencedirect.com/science/article/pii/S034181622300406X).

Melesse, A.M., S. Ahmad, M.E. McClain, X. Wang, and Y.H. Lim. 2011.

Suspended sediment load prediction of river systems: An artificial neural network approach, Agricultural Water Management, Volume 98, Issue 5, Pages 855-866, ISSN 0378-3774, https://doi.org/10.1016/j.agwat.2010.12.012.

(https://www.sciencedirect.com/science/article/pii/S0378377410003951)

New Mexico Aquatic Invasive Species (NM AIS) Advisory Council. 2008. New Mexico Aquatic Invasive Species (NM AIS) Management Plan. October.

New Mexico Department of Agriculture. 2020. Noxious and Troublesome Weeds of New Mexico. Retrieved from https://pubs.nmsu.edu/_circulars/CR698/#a9

New Mexico Department of Game and Fish (NMDGF). (2022). 2022 Statewide Fisheries Management Plan.

Approved by the New Mexico State Game Commission. Retrieved from https://wildlife.dgf.nm.gov/download/nmdgf-fisheries-management-plan- 2022/?wpdmdl=45515&refresh=678011a169bcf1736446369

NMDGF Aquatic Invasive Species. Accessed 2/12/25. Aquatic Invasive Species - NMDGF

Persaud, D., Jaagumagi, R., and A. Hayton, 1992. Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario. Ontario Ministry of the Environment, Queen's Printer for Ontario.

Pfingsten, I.A., L. Berent, C.C. Jacono, and M.M. Richerson., 2025, Myriophyllum spicatum L.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?Species_ID=237&Potential=N&Type=0&HUCNumbe r=DGreatLakes , Revision Date: 8/8/2024, Access Date: 1/9/2025

Smith, Roy. 1998. Regional Guidance on Handling Chemical Concentration Data Near the Detection Limit in Risk Assessments. United States Environmental Protection Agency, Region 3 Hazardous Waste Management Division Office of Superfund Programs. 1650 Arch St. Philadelphia, PA 19103-2029.

van Wijk, Dianneke., Janse, Jan H ., Wang, Mengru., Kroeze, Carolien., Mooij, Wolf M,. and Janssen, Annette B.G. 2024.How nutrient retention and TN:TP ratios depend on ecosystem state in thousands of Chinese lakes, Science of The Total Environment, Volume 918, 170690, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv 2024.170690.

Wang, Shuhang., Li, Xizhi., Xia. Jiang., Yang. Zhang., Jinbo. Zhang., Yanxiao, Liu., Huaicheng, Guo., Zheng, Li., and Zhenghui, Fu. 2024The interaction between nutrients and heavy metals in lakes and rivers entering lakes, Ecological Indicators, Volume 161.

APPENDIX A: FIELD NOTES

Project: Sediment Sampling – Glenwood Pond

Crew:

Dai Thomas, Jelena Grbic

Date: 11-04-2024

Sample ID: Glenwood Pond Inlet / S1

Time: 16:50 Weather: Sunny, high 50˚F

Easting: 2403205.45 Northing: 845892.31 Depth: ~ 3 feet

Other Notes:

likely high in organic matter; Cobble/rock hit during sampling within a shallow depth Northeast end of pond and approximately near inlet Algae/vegetation covering almost all of pond, making it difficult to kayak trees surrounding riparian area with open areas for fishing.

Bottom of pond felt firm when pushing sediment sampler in.

Photo No: Photo

1 20241104_GlenwoodPondInlet_Core

2 20241104_GlenwoodPondInlet_Sediment

Sample ID: Glenwood Pond Outlet / S2

Time: 17:05 Weather: Sunny, high 50˚F

Easting: 2403058.26 Northing: 845697.74 Depth: ~ 4 feet

Other Notes:

Southeast end of pond high in organic matter Algae/vegetation covering almost all of pond, making it difficult to kayak trees surrounding riparian area with open areas for fishing.

Bottom of pond felt soft when pushing sediment sampler in.

Photo No: Description

1 20241104_GlenwoodPondOutlet_Core

2 20241104_GlenwoodPondOutlet_Sediment

APPENDIX B: SEDIMENT SAMPLE LAB TEST RESULTS

ANALYTICAL REPORT

PREPARED FOR

Attn: Corinne Fox

Tetra Tech Inc 6121 Indian School Road NE

Suite 205 Albuquerque, New Mexico 87110

Generated 12/5/2024 8:26:55 AM

JOB DESCRIPTION

NMDGF Sediment Sampling

Glenwood Pond and Snow Lake

JOB NUMBER

885-14977-1

See page two for job notes and contact information.

Albuquerque NM 87109 4901 Hawkins NE Eurofins Albuquerque https://eol.et.eurofinsus.com/myEOL/

Eurofins Albuquerque

Job Notes

The test results in this report relate only to the samples as received by the laboratory and will meet all requirements of the methodology, with any exceptions noted. This report shall not be reproduced except in full, without the express written approval of the laboratory. All questions should be directed to the Eurofins Environment Testing South Central, LLC Project Manager.

Authorization

Generated

12/5/2024 8:26:55 AM

Authorized for release by Cheyenne Cason, Project Manager cheyenne.cason@et.eurofinsus.com (505)345-3975

Page 2 of 29 12/5/2024

Table of Contents

Client: Tetra Tech Inc Project/Site: NMDGF Sediment Sampling

Laboratory Job ID: 885-14977-1 SDG: Glenwood Pond and Snow Lake

Eurofins Albuquerque

12/5/2024

Cover Page

Table of Contents

Definitions/Glossary

Case Narrative

Client Sample Results

QC Sample Results

QC Association Summary

Lab Chronicle

Certification Summary

Chain of Custody

Receipt Checklists

Definitions/Glossary Job ID: 885-14977-1Client: Tetra Tech Inc

SDG: Glenwood Pond and Snow LakeProject/Site: NMDGF Sediment Sampling

Qualifiers

Metals Qualifier Description

J Result is less than the RL but greater than or equal to the MDL and the concentration is an approximate value.

Qualifier

General Chemistry Qualifier Description

4 MS, MSD: The analyte present in the original sample is greater than 4 times the matrix spike concentration; therefore, control limits are not applicable.

Qualifier

Glossary These commonly used abbreviations may or may not be present in this report.

☼ Listed under the "D" column to designate that the result is reported on a dry weight basis

Abbreviation

%R Percent Recovery

CFL Contains Free Liquid

CFU Colony Forming Unit

CNF Contains No Free Liquid

DER Duplicate Error Ratio (normalized absolute difference)

Dil Fac Dilution Factor

DL Detection Limit (DoD/DOE)

DL, RA, RE, IN Indicates a Dilution, Re-analysis, Re-extraction, or additional Initial metals/anion analysis of the sample

DLC Decision Level Concentration (Radiochemistry)

EDL Estimated Detection Limit (Dioxin)

LOD Limit of Detection (DoD/DOE)

LOQ Limit of Quantitation (DoD/DOE)

MCL EPA recommended "Maximum Contaminant Level"

MDA Minimum Detectable Activity (Radiochemistry)

MDC Minimum Detectable Concentration (Radiochemistry)

MDL Method Detection Limit

ML Minimum Level (Dioxin)

MPN Most Probable Number

MQL Method Quantitation Limit

NC Not Calculated

ND Not Detected at the reporting limit (or MDL or EDL if shown)

NEG Negative / Absent

POS Positive / Present

PQL Practical Quantitation Limit

PRES Presumptive

QC Quality Control

RER Relative Error Ratio (Radiochemistry)

RL Reporting Limit or Requested Limit (Radiochemistry)

RPD Relative Percent Difference, a measure of the relative difference between two points

TEF Toxicity Equivalent Factor (Dioxin)

TEQ Toxicity Equivalent Quotient (Dioxin)

TNTC Too Numerous To Count

Eurofins Albuquerque

Page 4 of 29 12/5/2024

Job Narrative 885-14977-1

Analytical test results meet all requirements of the associated regulatory program listed on the Accreditation/Certification Summary Page unless otherwise noted under the individual analysis. Data qualifiers and/or narrative comments are included to explain any exceptions, if applicable.

Matrix QC may not be reported if insufficient sample is provided or site-specific QC samples were not submitted. In these situations, to demonstrate precision and accuracy at a batch level, a LCS/LCSD may be performed, unless otherwise specified in the method.

Surrogate and/or isotope dilution analyte recoveries (if applicable) which are outside of the QC window are confirmed unless attributed to a dilution or otherwise noted in the narrative.

Regulated compliance samples (e.g. SDWA, NPDES) must comply with the associated agency requirements/permits.

Receipt The samples were received on 11/7/2024 10:51 AM. Unless otherwise noted below, the samples arrived in good condition, and, where required, properly preserved and on ice. The temperature of the cooler at receipt time was 10.9°C.

Receipt Exceptions The Field Sampler was not listed on the Chain of Custody.

The following samples were received at the laboratory outside the required temperature criteria: Glenwood Pond Inlet (885-14977-1), Glenwood Pond Outlet (885-14977-2), Snowlake Downstream (SS2) (885-14977-3), Snowlake Center (SS3) (885-14977-4) and Snowlake Upstream (SS1) (885-14977-5). This does not meet regulatory requirements. The client was contacted regarding this issue, and the laboratory was instructed to proceed with analysis.

HPLC/IC

No additional analytical or quality issues were noted, other than those described above or in the Definitions/ Glossary page.

Metals No additional analytical or quality issues were noted, other than those described above or in the Definitions/ Glossary page.

General Chemistry Method 365.1: The matrix spike / matrix spike duplicate (MS/MSD) recoveries for preparation batch 860-200139 and analytical batch 860-201372 were outside control limits. Sample matrix interference is suspected because the associated laboratory control sample (LCS) recovery was within acceptance limits.

Method 4500NH3_C_TKN: A deviation from the Standard Operating Procedure (SOP) occurred. Details are as follows: K2SO4-DI mixture tank did not have the .5g of K2SO4 added. QC passing. Data valid.

No additional analytical or quality issues were noted, other than those described above or in the Definitions/ Glossary page.

Case Narrative Client: Tetra Tech Inc Job ID: 885-14977-1 Project: NMDGF Sediment Sampling

Eurofins Albuquerque

Job ID: 885-14977-1 Eurofins Albuquerque

Page 5 of 29 12/5/2024

Client Sample Results

SDG: Glenwood Pond and Snow LakeProject/Site: NMDGF Sediment Sampling

Lab Sample ID: 885-14977-1Client Sample ID: Glenwood Pond Inlet Matrix: SolidDate Collected: 11/04/24 16:50

Date Received: 11/07/24 10:51

Method: EPA 300.0 - Anions, Ion Chromatography

RL

ND 1.5 mg/Kg 11/11/24 08:28 11/11/24 15:10 5

Analyte Dil FacAnalyzedPreparedUnit DResult Qualifier

Nitrate

1.5 mg/Kg 11/11/24 08:28 11/11/24 15:10 5NDNitrite

Method: SW846 6010B - Metals (ICP)

RL

3500 62 mg/Kg 11/08/24 12:34 11/11/24 14:54 20

Analyte Dil FacAnalyzedPreparedUnit DResult Qualifier

Aluminum

0.51 mg/Kg 11/08/24 12:34 11/11/24 14:19 221Manganese

1.0 mg/Kg 11/08/24 12:34 11/11/24 14:19 22.5Nickel

5.1 mg/Kg 11/08/24 12:34 11/11/24 14:19 223Zinc

Method: SW846 6020A - Metals (ICP/MS)

RL

ND 10 mg/Kg 11/08/24 12:34 11/24/24 16:50 100

Analyte Dil FacAnalyzedPreparedUnit DResult Qualifier

Arsenic

10 mg/Kg 11/08/24 12:34 11/24/24 16:50 100NDCadmium

21 mg/Kg 11/08/24 12:34 11/24/24 16:50 100NDChromium

10 mg/Kg 11/08/24 12:34 11/24/24 16:50 100NDLead

10 mg/Kg 11/08/24 12:34 11/24/24 16:50 100NDSilver

16 mg/Kg 11/08/24 12:34 12/03/24 15:24 100NDCopper

General Chemistry

RL

29 5.0 mg/Kg 11/15/24 15:48 11/21/24 17:38 5

Analyte Dil FacAnalyzedPreparedUnit DResult Qualifier

Total Phosphorus as P (EPA 365.1)

49 mg/Kg 11/12/24 10:55 11/12/24 16:06 1110Ammonia (SM 4500 NH3 C)

130 mg/Kg 11/22/24 08:54 11/25/24 15:55 11500Nitrogen, Total Kjeldahl (SM 4500

NH3 C)

0.50 mg/Kg 11/15/24 14:54 11500Nitrogen, Total (EPA Total Nitrogen)

Eurofins Albuquerque

Page 6 of 29 12/5/2024

SDG: Glenwood Pond and Snow LakeProject/Site: NMDGF Sediment Sampling

Lab Sample ID: 885-14977-2Client Sample ID: Glenwood Pond Outlet Matrix: SolidDate Collected: 11/04/24 17:05

Date Received: 11/07/24 10:51

Method: EPA 300.0 - Anions, Ion Chromatography

RL

ND 1.5 mg/Kg 11/11/24 08:28 11/11/24 15:30 5

Analyte Dil FacAnalyzedPreparedUnit DResult Qualifier

Nitrate

1.5 mg/Kg 11/11/24 08:28 11/11/24 15:30 5NDNitrite

Method: SW846 6010B - Metals (ICP)

RL

11000 150 mg/Kg 11/08/24 12:34 11/11/24 15:12 50

Analyte Dil FacAnalyzedPreparedUnit DResult Qualifier

Aluminum

0.49 mg/Kg 11/08/24 12:34 11/11/24 14:31 290Manganese

0.99 mg/Kg 11/08/24 12:34 11/11/24 14:31 28.5Nickel

4.9 mg/Kg 11/08/24 12:34 11/11/24 14:31 232Zinc

Method: SW846 6020A - Metals (ICP/MS)

RL

ND 9.9 mg/Kg 11/08/24 12:34 11/24/24 16:54 100

Analyte Dil FacAnalyzedPreparedUnit DResult Qualifier

Arsenic

9.9 mg/Kg 11/08/24 12:34 11/24/24 16:54 100NDCadmium

20 mg/Kg 11/08/24 12:34 11/24/24 16:54 100NDChromium

9.9 mg/Kg 11/08/24 12:34 11/24/24 16:54 10013Lead

9.9 mg/Kg 11/08/24 12:34 11/24/24 16:54 100NDSilver

16 mg/Kg 11/08/24 12:34 12/03/24 15:28 100NDCopper

General Chemistry

RL

17 0.98 mg/Kg 11/15/24 15:48 11/21/24 17:21 1

Analyte Dil FacAnalyzedPreparedUnit DResult Qualifier

Total Phosphorus as P (EPA 365.1)

25 mg/Kg 11/12/24 10:55 11/12/24 16:06 163Ammonia (SM 4500 NH3 C)

53 mg/Kg 11/22/24 08:54 11/25/24 15:55 1490Nitrogen,…